کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1608131 1516243 2015 7 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Effects of brazing temperature on microstructure and mechanical performance of Al2O3/AgCuTi/Fe–Ni–Co brazed joints
موضوعات مرتبط
مهندسی و علوم پایه مهندسی مواد فلزات و آلیاژها
پیش نمایش صفحه اول مقاله
Effects of brazing temperature on microstructure and mechanical performance of Al2O3/AgCuTi/Fe–Ni–Co brazed joints
چکیده انگلیسی


• The dependence of seam microstructure on brazing temperature is discussed.
• Thermokinetic analysis is conducted to discuss interfacial reaction process.
• Reaction layer thickness is dependent on brazing temperature and holding time.
• The microcracks during tensile test form at the interface between Ti3Al and TiO.

Al2O3/Fe–Ni–Co joints are achieved using Ag–Cu–8Ti filler alloy, and the dependence of the joint microstructure and mechanical performance on the brazing temperature has been studied by means of SEM, EDS, XRD and tensile test. The results show that the brazing seam is composed of TiO, Ti3Al, Ag (s, s), Cu (s, s), (Cu, Ni) and Ni4Ti3 phases. A layer of Ti3Al and TiO products is observed at the Al2O3/AgCuTi interface and the fracture testing indicates that the thickness of the reaction layer plays a critical role in the joint strength. The joint strength firstly increases and then declines with the thickness of the (Ti3Al + TiO) layer increasing, and the formation of the cracks is ascribed to the existence of Ti3Al phase. The thermokinetic analysis for the interfacial reaction between Al2O3 and AgCuTi show that the Gibbs free energy equals −88.939 kJ/mol for forming Ti3Al and TiO phases, and the growth rate of the reaction layer mainly depends on the diffusion rate of Ti across the formed reaction layer. Meanwhile, the quantitative relationship among brazing temperature, holding time and reaction layer thickness has been established.

The theoretical curve of brazing time and thickness is close proximity to the measured values, which means the extracted mathematical relationship (X = 2.2616 × 10−1 exp (−143.85 × 103/8.314 T) × t0.5) relatively closed to the actual situation. The growth rate of reaction layer declines with the increase of brazing time, and this phenomenon indicates that the diffusion rate of Ti atoms across the reaction layer is less than the rate of the chemical reaction during brazing, that is, the growth rate of reaction layer mainly depends on the diffusion rate of Ti atoms across the formed reaction layer.Figure optionsDownload as PowerPoint slide

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Alloys and Compounds - Volume 650, 25 November 2015, Pages 30–36
نویسندگان
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